When a mobile phone is used by a user to photograph planar rectangular objects such as calligraphy and painting works, posters and documents, since a camera is usually failed to be placed on a vertical line at a central point of the object, which is perpendicular to a plane of the object, the rectangular object is presented as a trapezoidal object on a screen due to a perspective relation after being photographed. As a result, the display effect is seriously affected and the user experience is poor.
No function for correcting a tilt of a plane of a subject due to the photographing angle is found in a camera application of a current terminal product such as a mobile phone. Generally, the following two solutions are adopted by the user to prevent the plane of the subject from being tilted:
(1) enabling the camera of the mobile phone to be placed on the vertical line at the center point of the object, which is perpendicular to the plane of the object, as far as possible. However, if the area of the subject is too large or the subject is placed on the ground, such solution is hard to be achieved, or the user's feet might be shot during high angle shot.
(2) importing captured pictures into a computer or a mobile phone library and opening the pictures by the user, and then, through a mapping software or mobile phone picture editing software in the computer, selecting and stretching corner points of the picture so as to change the object being turned into a trapezoidal subject through the perspective relation back to a rectangular subject. Although such solution can correct the tilt through straightening, the picture is edited in the library after being captured in such solution. Therefore, a process of the solution is complicated because there are many steps such as importing and editing the picture, causing that many users often do not know how to perform editing operations and the final effect cannot be achieved in one time and timely. For the user, it is required to perform one operation of photographing and saving and one operation of editing and saving, and thus a lot of steps need to be implemented. That is to say, such solution has poor convenience, is difficult to be grasped by many non-professional users and cannot achieve desired effects.
As can be seen from the above analysis, the above two solutions implemented in a physical or software manner are poor in both convenience and operability, resulting in poor user experience.